1. Field of the Invention
The present invention relates to an optical disc and an optical disc apparatus. Specifically, in the present invention, optical discs in formats and/or recording modes different from each other are designed to have a different synchronization pattern of a signal obtained by reading positional information embedded in guide grooves irradiated with a light spot. In addition, in the present invention, an optical disc apparatus easily identifies whether the optical disc mounted thereto is an optical disc having a standard density or an optical disc having a high density by distinguishing their synchronization patterns from each other.
2. Description of the Related Art
In recent years, there is an increasing demand for a recording media having a larger capacity. As to an optical disc, in order to increase its recording density, methods such as narrowing its track pitches, shortening the minimum length of the recording bit have been suggested.
As to an optical disc satisfying the standard of a compact disc, for example, a write once optical disc (CD-R) and a rewritable optical disc (CD-RW) standardized in ISO/IEC13490-1, there is also a demand for increasing their recording capacity, in order that they can record larger amount of data.
When a write once optical disc or a rewritable optical disc provided with a large capacity is mounted to an optical disc apparatus for recording and reproducing a signal into or from the optical disc, the following operation is required for the optical disc apparatus. That is, the optical disc recording apparatus is required to quickly and easily identify whether the optical disc is an optical disc provided with a large recording capacity (hereinafter, referred to as a large density optical disc), or an optical disc having a standard recording capacity (hereinafter, referred to as a standard density optical disc) in formats and/or recording modes different from each other. If the apparatus cannot quickly and easily identify the optical disc, it cannot conduct a recording and reproducing operation suitable for each type of optical disc. For example, if the optical disc apparatus cannot identify whether or not the optical disc is a high density optical disc before demodulating data which has been recorded in an optical disc, the optical disc apparatus also cannot judge whether or not a processing designed specifically for a high density optical disc and a hardware exclusive to the high density optical disc are necessary. In this case, the optical disc apparatus requires a complicated processing for recognizing the type of the optical disc.
As to an optical disc into which no data is recorded (i.e. a blank disc), it is impossible to identify it by use of recorded data. Therefore, the blank disc is required to have information from which the blank disc can be identified beforehand.
In view of the aforementioned problems in the prior arts, the present invention has been conducted to provide an optical disc which can be easily identified whether or not it is an optical disc in a format and/or recording system different from the other optical disc, and an optical disc apparatus.
An optical disc of the present invention can conduct recording operation, and positional information is embedded in its guide grooves irradiated with a light spot. In the optical disc, a synchronization pattern of a signal obtained by reading the positional information is made to be different from a synchronization pattern of the other optical disc in a different format and/or recording mode.
Furthermore, an optical disc is capable of conducting recording operation and includes guide grooves for guiding a light spot in which positional information is embedded. The positional information is recorded by wobbling the guide grooves by a specified modulation mode, and the positional information has a specified synchronization signal including a synchronization pattern different from a synchronization pattern of a synchronization signal included in the positional information recorded in the other optical disc, having a recording density lower than a recording density of the optical disc, by the specified modulation mode.
An optical disc apparatus according to the present invention uses plural kinds of optical discs each of which can conduct recording operation, each of which includes positional information embedded in its guide grooves irradiated with a light spot, and each of which includes synchronization pattern that is obtained by reading the positional information and is made to be different from the synchronization pattern of the other optical discs in accordance with their format and/or recording modes, comprising: a positional information reading device for reading the positional information; and an identifying device for identifying the kind of the optical disc by recognizing a synchronization pattern of a signal obtained in the positional information reading device. In addition, the optical disc apparatus includes a position clarifying device for clarifying the position irradiated with a light spot from a signal obtained in the positional information reading device, and the position clarifying device clarifies the position irradiated with the light spot based on the result of the identification in the identifying device.
Furthermore, an optical disc apparatus scans first and second optical discs by a light spot to record and/or reproduce data in or from the first and second optical discs. The first and second optical discs are capable of conducting recording operation and formed with guide grooves for guiding the light spot in which positional information is embedded. The positional information is recorded into the optical discs by wobbling the guide grooves by a specified modulation mode. The positional information recorded in the first optical disc has a specified synchronization signal including a synchronization pattern different from a synchronization pattern of a synchronization signal included in the positional information recorded in the second optical disc having a recording density lower than a recording density of the first optical disc. The optical disc apparatus includes: a reproducing device for decoding the wobbled positional information; and an identifying device for identifying the first and second optical discs by recognizing the synchronization pattern included in the optical information read from the first and second optical discs.
In the present invention, for example, wobbles are formed as positional information in guide grooves irradiated with a light spot. A wobble component is extracted from each wobble to produce a synchronization pattern of a wobble signal. In this case, a high density optical disc and a standard density optical disc are manufactured in such a manner that their synchronization patterns of the wobble signal are different from each other. When, for example, a signal produced by reading a positional information from the optical disc is a bi-phase modulated signal, defining the minimum channel bit of the signal as xe2x80x9cTxe2x80x9d, the synchronization pattern is set to have a pattern with xe2x80x9c3Txe2x80x9d or more, and also is set to have a DSV value of xe2x80x9c0xe2x80x9d.
An optical disc apparatus to which the optical disc obtained in the above-described manner is mounted clarifies the synchronization pattern of the optical disc, and identify whether the optical disc is a high density optical disc or a standard density optical disc, based on the result of the clarification of the synchronization pattern. Based on the result of the identification of the optical disc, the signal is recorded or reproduced into or from the optical disc.